Effect of Injection Parameters and Wall-Impingement on Atomization and Gas Entrainment Processes in Diesel Sprays

Mohammadi, Ali; Kidoguchi, Yoshiyuki; Miwa, Kei

doi:10.4271/2002-01-0497

Cited by 28 publications

(10 citation statements)

References 5 publications

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“…Bruneaux et al 11 studied the air entrainment of an impinging spray and determined that spray/wall interaction also plays a role in air entrainment before impingent occurs. Mohammadi et al 12 investigated ambient air entrained processes in detail by applying the laser sheet imaging method. It is concluded that a higher injection pressure, larger orifice diameter or shorter impinging distance can enhance gas entrainment under impinging condition.…”

Section: Introductionmentioning

confidence: 99%

Effect of split injection on mixture formation and combustion processes of diesel spray injected into two-dimensional piston cavity

Yang

Yamakawa

Nishida

et al. 2017

Proceedings of the Institution of Mechanical Engineers, Part D:

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The objective of this study is to obtain an enhanced understanding of the effect of split injection on mixture formation and combustion processes of diesel spray. A two-dimensional (2D) piston cavity of the same shape as that used in a small-bore diesel engine was employed to form the impinging spray flame. The fuel was injected into a high pressure, high temperature constant volume vessel through a single-hole nozzle with a hole diameter of 0.11 mm. The injection process comprised a pre-injection followed by the main injection. The main injection was carried out either as a single injection of injection pressure 100 MPa (Pre + S100), or by two types of split injection of injection pressure 160 MPa. The latter two types were defined by mass fraction ratios 1:1 and 3:1 (Pre + D160_1-1, Pre + D160_3-1). In order to observe the spray mixture formation process, the tracer laser absorption scattering (LAS) techique was adopted. Tracer LAS fuel with 97.5 vol% of n-tridecane and 2.5 vol% of 1-methylnaphthalene (a-MN) was employed. The spatial distributions of the vapor and liquid phases and the spray mixture formation characteristics in the 2D piston cavity for the three injection strategies were investigated. The diesel spray combustion and soot formation processes were studied using a highspeed video camera. The flame structure and soot formation process were examined using two-color pyrometry. The experimental results revealed that the split-injection vapor distribution was significantly more homogeneous than that of the single injection. The main injection fuel caught up with the pre-injection fuel and provided the spray tip with substantial additional momentum, enabling it to advance further. A high soot concentration and low temperatures appeared near the cavity wall region under the three injection strategies. The soot reduction rate for split injection was higher than that for single injection. The second main injection caught up with the previous injection's flame, which deteriorated the combustion and resulted in higher soot generation. The effect of split injection on the process of soot evolution finished at the same time as that of single injection.

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Section: Introductionmentioning

confidence: 99%

Effect of split injection on mixture formation and combustion processes of diesel spray injected into two-dimensional piston cavity

Yang

Yamakawa

Nishida

et al. 2017

Proceedings of the Institution of Mechanical Engineers, Part D:

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“…In small-bore high-pressure fuel-injected diesel engines, spray-wall impingement occurs and plays a significant role in mixture formation, combustion and emissions. As a result, the effect of the spray-wall interaction has become an important subject for many research workers during the past few decades, including mixture formation, [1][2][3][4][5][6][7][8] combustion and soot emissions. [9][10][11][12][13][14] These investigations conducted by previous researchers have produced much valuable information which can provide some basic theories for the study of the effect of the spray-wall interaction on the diesel spray flame behaviours.…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, it was confirmed that ambient gas entrainment was enhanced by impingement. 4,6 However, a fuel film was formed after impingement, which caused poor combustion and undesirable emissions. As the direct result of the mixture formation, the combustion process was also influenced by the impinging effect.…”

Section: Introductionmentioning

confidence: 99%

Effect of flat-wall impingement on diesel spray combustion

Li¹,

Nishida²,

Ogata³

et al. 2014

Proceedings of the Institution of Mechanical Engineers, Part D:

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The effect of spray–flat-wall interaction on the diesel combustion characteristics in a constant-volume vessel was investigated. A flat wall was fixed perpendicular to the nozzle hole axis. Three injection pressures of 100 MPa, 150 MPa and 200 MPa and a single nozzle hole with a diameter of 0.133 mm were employed. Mie scattering was adopted to detect the spray formation process; OH* chemiluminescence and natural colour luminosity were conducted to analyse the combustion process. The two-colour method was applied to calculate the soot emissions and the temperature distribution. The results reveal that, in comparison with a free spray flame, flat-wall impingement causes diesel combustion to deteriorate when the liquid phase–wall interaction occurs; however, when an appropriate impinging distance (longer than liquid-phase penetration) is selected, combustion is observed to be enhanced. As for the impinging spray flame, when the injection pressure is increased, soot formation decreases; however, combustion is not linearly enhanced by increasing the injection pressure, and the OH* chemiluminescence intensity achieves the highest value with an injection pressure of 150 MPa.

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“…Two folded sheets (2) are attached to the protective cap and also are holding two fixed 'U' shaped structures (3) which are responsible to bear the wall arrangement at its determined distance-angle configuration. Those different configuration are possible due to six pairs of exchangeable lateral frames (4). Each set of those frames is used depending on the desired distance-angle arrangement.…”

Section: Wall Supporting Systemmentioning

confidence: 99%

“…This phenomenon plays a fundamental role in the mixing and evaporation of fuel [1]- [3], combustion behaviour and the formation of pollutant emissions [4]- [6]. Despite the growing interest around this field and the various efforts in its research [1]- [6], the impact of spray with a wall is a subject of difficult analysis both theoretically and experimentally due to the highly transient nature of the spray and the high spatio-temporal variability of the event.…”

Section: Introductionmentioning

confidence: 99%

Spray/wall interaction analysis on an ECN single-hole injector at diesel-like conditions through Schlieren visualization.

Payri

Peraza

Bazyn

2017

Proceedings ILASS–Europe 2017. 28th Conference on Liquid Atomization and Spray Systems

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To continuously improve CFD models which simulate spray evolution, breakup and evaporation mechanisms, it is helpful to validate them with results obtained by experimental research. In the present study, a mono-orifice target nozzle from Engine Combustion Network, referred to as Spray D, was investigated at conditions of spray-wall interaction, which actually is a real situation in internal combustion engines that is not frequently analyzed by visualization. A Photron SA-X2 high-speed camera was employed to record the vapor phase development of the spray in an inert atmosphere using a Schlieren imaging single-pass setup. The experiments show that the spreading of the spray along the wall has a behavior fairly similar to penetration at free-jet situations, especially regarding to its susceptibility to the operating conditions and its proportionality to the square root of time once the spray reaches a steady regime interacting with the wall. Furthermore, the spray film thickness was measured at three distances from the spray-wall impact point during the injection event, thereby characterizing that parameter both spatially and temporally. The tests were carried out in a constant pressure-flow facility able to reproduce pressure and temperature conditions, similar to those seen into a diesel engine. In order to observe the behavior of the spray colliding with a wall within this test rig, a system capable to being fitted into it and to holding a fused quartz wall at different injector tip-wall distances and impingement angle configurations, was designed and employed. IntroductionAt present, the study of the spray-wall interactions into the field of transportation systems is increasingly relevant in a world aimed at reducing the displacement per cylinder of the internal combustion engines. This phenomenon plays a fundamental role in the mixing and evaporation of fuel , the impact of spray with a wall is a subject of difficult analysis both theoretically and experimentally due to the highly transient nature of the spray and the high spatio-temporal variability of the event. Because of this, its effects on the engine performance are not entirely known. On the one hand, the incidence and accumulation of fuel in the cylinder walls can lead to the formation of a fuel film that worsens combustion, promotes the emission of carbon monoxide and unburned hydrocarbons and involves energy losses given the increase of heat transfer [7]. On the other hand, the impact of the spray with a surface tends to improve the mixing of the fuel in the air due to both the impact and the subsequent expansion of the front of the jet. The complexity of the jet-wall impact phenomenon has to be added to the overall complexity of the injection-combustion processes, which, although they have been extensively studied in 'free jet' conditions [7]-[9] remain an active area of research.

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Effect of Injection Parameters and Wall-Impingement on Atomization and Gas Entrainment Processes in Diesel Sprays

Cited by 28 publications

References 5 publications

Effect of split injection on mixture formation and combustion processes of diesel spray injected into two-dimensional piston cavity

Effect of split injection on mixture formation and combustion processes of diesel spray injected into two-dimensional piston cavity

Effect of flat-wall impingement on diesel spray combustion

Spray/wall interaction analysis on an ECN single-hole injector at diesel-like conditions through Schlieren visualization.

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